Azelaic acid-diamine reaction product deicer



United States Patent P AZELAIC ACID-DIAMINE REACTION PRODUCT DEICER Harry Andress, Jr., Pitman, N.J., assignor to Socony MObll Oil Company, Inc., a corporation of New York No Drawing. Filed Dec. so, 1958, 'Ser. No. 783,679 3 Claims. 0.44-71 This invention relates to gasoline compositions adapted to improve the operation of internal combustion engines. It is more particularly-concerned withmotor fuels that provide improved engine operation under cool, humid weather conditions.

As is well known to those skilled in the art, frequent stalling of automobile engines, especially during the warmup period, has been a common occurrence. This difficulty is most pronounced in postwar cars having automatic transmissions and a consequent limit on the maximum permissible idle speed, although it also occurs in cars without automatic transmissions. Stalling of this type, of course, is a definite safety hazard, as well as a decided inconvenience in frequent restarting of the engine.

It is now recognized that stalling during the warmup period is attributable to the for'mation of ice on the throttle plate and the carburetor barrel near it. The water which forms the ice does not come from the gasoline, i.e., as entrained water, but from the air that enters the carburetor. As has been mentioned hereinbefore, stalling generally occurs in cool, humid weather, when the temperatures are above about 30 F. and below about 60 F. and the relative humidity is about 65 percent and higher, up to 100 percent. The most critical conditions are temperatures of 35-40 F. and 100 percent relative humidity.

As the gasoline evaporates in the carburetor, it reduces the temperature of the surrounding metal by as much as 40 F. Moisture in the incoming air comes in contact with these parts and begins to build up ice on the throttle plate and in the carburetor barrel. The more moist this air is, the greater the buildup of ice. Then, when the engine is idled, the throttle plate closes and the ice chokes off the normal small flow of air through the small clearance between the throttle plate and the carburetor wall. This causes vthe engine to stall. The engine can usually be restarted when the heat from the exhaust manifold melts the ice sufliciently. However, stalling will continue until the engine is completely warmed up.

Icing may also occur in the carburetors of some vehicles when cruising at speeds of 30-60 'rn.p .h. Such icing is a particular problem in the case of certain trucks and cars equipped with carburetors having Venturi-type fuel-air mixing tubes (emulsion tubes). Such carburetors are found in trucks and in manyEuropean .cars. The ice builds up in the tube and restricts the flow of air, thereby enriching the fuel mixture and. reducing efiiciency. Eventually the engine may stall.

Gasoline is a mixture of hydrocarbons having an initial boiling point falling between about 75". F. and about 135 F. and an end-boiling point falling between about 250 F. and about 450 F. The boiling range of the gasoline, of course, reflects on its volatility. Thus, a higher boiling gasoline will be less volatile and give less stalling difliculty. It has been proposed in the art that a gasoline having an A.S.T.M. mid-boiling (50%) point of 310 F. or higher will not be subject to stalling. Although thismay be the case for a given series of gasolines, however, it is will overcome stalling 2 not the sole and controlling factor. mid-boiling point but a low initial boiling point (e.g.,' full boiling range gasolines) can induce stalling when the aforementioned stall-inducing atmospheric conditions are prevalent. Thus, any gasoline will give difiiculty in damp,

cool weather. In modern engine operation, however, control of stalling by means of volatility is not feasible, be cause other performance characteristics are affected.

It has now been found that stalling during engine warmup can be overcome simply and economically. It has been discovered that small amounts of certain acidamine reaction products, when added to motor gasoline,

difiiculties attributable to carburetor icing.

Accordingly, it is an object of this invention to provide an improved motor fuel. Another object. is to provide a motor fuel adapted to prevent stalling during engine warmup in cool, humid weather. A specific object is to provide an antistall gasoline containing certain acid,- amine reaction products. Other objects and advantages .of this invention will become apparent to those skilled in k the art, from the following detailed description.

In general, this invention provides a motor gasoline containing a small amount, sufiicient to inhibit stalling, of the reaction product of an N-alkyl diamine of the structure RNHCH CH CH NH wherein R is a mixture of aliphatic hydrocarbon radicals containing between about 14 carbon atoms and about 18 carbon atoms, and azelaic acid, in a molar ratio of 2: 1, respectively.

The reaction product utilizable herein is produced by reacting azelaic acid with anamine of the formula, RNHCH CH CH NH wherein R is an aliphatic hydrocarbon radical having between 14 and 18 carbon atoms. Non-limiting examples of the amine reactant are N-tetradecyl propylenediamine, N-hexadecyl propylenediamine, N-hexadecenyl propylenediamine, N'octadecyl propylenediamine, and N-octadecenyl propylenediamine. The amine reactant can be a single amine or a mixture of two or more of the amines defined hereinabove.

The reaction between the amine reactant and the azelaic acid is carried out at a molar ratio of about 2:1, respectively. The reaction is a condensation reaction. Accordingly, it is carried out vunder conditions whereby 'water of condensation is formed. In general, the reaction tween about 4 and about 8 hours, until two moles of water per mole of azelaic acid reactant are evolved. The water formed during the reactioncan be removed by any method usual in the art. Feasibly, it is removed by azeotropic distillation with a non-polar solvent, such as benzene, toluene,-and xylene. The solvent can be removed from the reaction product, as by topping under vacuum. Removal is not necessary, however, as the solvent will not impair the effectiveness of the reaction product as a gasoline additive.

'The amount of the aforedescribed reaction product that is added to the motor gasoline will. vary between about- 0.005 percent and about 0.5 percent,-by weight, of the gasoline. In preferred practice, amounts varying between about 0.01 percent and about 0.05 percent, by weight,

are used.

The antistall additives of the invention may be used in the gasoline along with other antistall addition agents or other additives designed to impart other improved properties thereto. Thus, anti'knock agents, p're-ignition inhibitors, anti-rust agents, metal-deactivators, dyes, antioxidants, detergents, etc., may be present in the gasoline. Also, the gasoline may contain a small amount, from about 0.01 percent to about 1 percent, by weight, of a solvent oil or upperlube. Suitable oils, for example, include Coastal and Mid-Continent distillate oils having Patented May 2, 1961 Gasolines of higher 3 viscosities within the range of from about 50 to about 500 S.U.S. at 100 F. Synthetic oils, such as diester oils, polyalkylene glycols, silicones, phosphate .esters, polypropylenes, polybutylenes and the like, may also-be used. The following examples are for the purpose of illustrating this invention and demonstrating the effectiveness thereof. This invention is not to be limited to the specific composition set forth in the examples or to the. operations and manipulations involved. Other materials and formulations as described hercinbefore can be used, as those skilled in the art will readily understand. The ability of an additive to inhibit icing is demonstrated in the following test:

HILLMAN-MINX ENGINE TEST A downdraft Solex FAI- carburetor was mounted on 'a standard 1953 Hillman-Minx engine. The engine was connected to a 7.5 horsepower induction motor and operated under load at 2800 rpm. This was equivalent to driving at about 40 miles per hour.

The Solex carburetor was especially prone to icing on its spraying well which'is located in the center of the carburetor throat. The spraying well is a cylindrical metal tube with apertures through which a fuel-air mixture is sprayed into the carburetor throat. Evaporation of the fuel refrigerates the spraying well.

As ice formed on the well it restricted the flow of air through the carburetor and caused a drop in pressure. This pressure change was recorded by a manometer connected above and below the point of ice deposition. Temperatures at'this pointwere measured by a thermocouple attached to the well. The entire carburetor was enclosed in an asbestos chamber that was connected to an ice tower. Air at 3437 F. and 90-100 percent relative humidity was passed through the carburetor at constant velocity. V

In conducting a test the engine was first run until the spraying well reached an equilibrium temperature of about 20-25 F. The fuel flow was then stopped and the engine was driven by the induction motor until the spraying well reached F. (warm ambient air was adr'nitted to the carburetor during this period), Fuel flow was now restored to the engine and the run was started. As the engine operated under load, ice deposited ,on the spraying well. The pressure drop across the ice formation was recorded at one minute intervals for 20 minutes. Several tests were, made on each fuel blend and the results were averaged.

' A fuel rating was obtamed by.using these pressure readings to calculate the percentage of the carburetor throat area that would be blocked with .ice after 20 minutes. The percent of annular area in the carburetor that is blocked by ice determines the amount of pressure drop across the annular opening in any given installation. Thus, for each carburetor, the amount of throat area blocked by ice is related to the amount ofpressure drop above and below the point of icedeposition. The relationship between pressure drop and area blocked was determined to calibrate the'carburetor, as followsa- A series of flanged cylinders were prepared,.which fitted over theemulsion tube and blocked a portion of the annular opening. Each tube had a different but known size flange. Thus, it was known what fraction of the annular area was blocked'by each flange. The engine was operated with a flanged cylinder in the carburetor and the amount of pressure drop was noted and recorded. This operation was repeated with each flange. t. From the data, thus obtained, the relationship between pressure drop and amount of throat area blocked was plotted. Then, when runs were made usingblanl; fuel or' inhibited (test) fuel, bnt'with 'no flanged inserts iri the carburetor, thethroat area blocked by ice was bdetermined from the amount of pressure drop. The average percent butane.

parison of a test fuel result with the result on the blank fuel gives a positive order of magnitude, i.e., one can say, for example, that an additive cut the amount of ice formation by some certain percentage.

The test gasoline was a blend, by volume, of 66 percent catalytically cracked gasoline, 2 percent natural gasoline, 12 percent benzene, 8 percent toluene, and 12 It had an A.S.T.M. boiling range of F. to 394 F., with a mid-boiling point of 200 F.

Example 7 The N-alkyl amine used in this run was a mixture, by weight, of about 2 percent N-tetradecyl propylene diamine, about 24 percent N-hexadecyl propylenediamine, about 71 percent N-octadecyl propylenediamine, and about 3 percent N-octadecenyl propylenediamine. A mixture of 200 grams (0.5 mole) of this amine and 50 grams (0.25 mole) of azelaic acid in xylene diluent were refluxed in'a reaction vessel provided with a reflux condenser and water take-off trap. The mixture was heated at 142 C. for 6 hours and at ISO-160 C. for 3 hours. Then, the reaction mixture was heated gradually to 250 C. and held at 250 C. for 3 additional hours. A total of 20 cc. of water was produced in the reaction.

Blends of the product of the example in three concentrations-in the test gasoline were prepared. These blends were subjected to the Hillman-Minx engine test.

- Pertinent data are set forth in Table I.

TABLE I I It will be apparent from the data'in Table I that the reaction products of this invention are-effective anti-' stall agents. Not all are equivalent in performance, but all will be effective t Although the present invention has been described with preferred embodiments, it is to be understood that modifications and variations may be resorted to, without departing from the spirit and scope of this invention, as those skilled in the artwill readily understand.- Such variations and modifications are considered to be within the purview and scope of the appended claims. a

.Whatisclaimedis: 1. A motor gasoline containing a small amount, sufficient to inhibit stalling, of the reaction product of an N-alkyl diamine of the structure RNHCH CH CH NH wherein R .is a mixtureof aliphatic hydrocarbon radicals containing between about 14 carbon atoms and about 18 carbon atoms, andazelaic acid, in a molar ratio of 2:1, respectively; said' reaction product being produced by heating at a temperature varying between about C; and about 300? C. and for between about 4 hours, and about 8 hours until 2 moles of .water have beeneyplvedperfmole of azelaic acid...

2." A motor gasoline containing between about 0.005

percent and about 0.5 percent, by weight, of the reaction product of an N-alkyl diamine of the structure RNHCHQCHQCHQNHQ, wherein R is a mixture of aliphatic hydrocarbon radicals containing between about 14 carbon atoms and about 18 carbon atoms, and az elaic acid, in a molar ratio of 2:1, respectively; said reaction product being produced by heating at a temperature varying between about 100 C. and about 300 C. and for between about 4 hours and about 8 hours until 2 moles of water have been evolved per mole of azelaic acid.

3. A motor gasoline containing between about 0.01 percent and about 0.05 percent, by weight, of the reaction product of an N-alkyl diamine of the structure RNHCH CH- CH NH wherein R is a mixture of aliphatic hydrocarbon radicals comprising, by weight, about 2 percent tetradecyl, about 24 percent hexadeeyl, about 71 percent octadecyl, and about 3 percent octadecenyl, and azelaic acid, in a molar ratio of 2:1, respectively;

temperature varying between about 100 C, and about 300 C. and for between about 4 hours and about 8 hours until 2 moles of water have been evolved per mole of azelaic acid.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Petroleum Refining With Chemicals, Kalichevsky and said reaction product being produced by heating at a 20 Kobe, Elsevier Pub. Co., 1956, page 480. 

1. A MOTOR GASOLINE CONTAINING A SMALL AMOUNT, SUFFICIENT TO INHIBIT STALLING, OF THE REACTION PRODUCT OF AN N-ALKYL DIAMINE OF THE STRUCTURE RNHCH2CH2CH2NH2, WHEREIN R IS A MIXTURE OF ALIPHATIC HYDROCARBON RADICALS CONTAINING BETWEEN ABOUT 14 CARBON ATOMS AND ABOUT 18 CARBON ATOMS, AND AZELAIC ACID, IN A MOLAR RATIO OF 2:1, RESPECTIVELY, SAID REACTION PRODUCT BEING PRODUCED BY HEATING AT A TEMPERATURE VARYING BETWEEN ABOUT 100*C. AND ABOUT 300*C. AND FOR BETWEEN ABOUT 4 HOURS AND ABOUT 8 HOURS UNTIL 2 MOLES OF WATER HAVE BEEN EVOLVED PER MOLE OF AZELAIC ACID. 